Method of treating metal powder



July 3, 1934. F. R. KEMMER v .1,964,853

METHOD 0F TRETING METAL POWDER n v Filed April 7, 1935 2f/Ye". Z.

ATTORNEY.

Patented July 3, 1934 UNITED STATES PATENT OFFICE 1,964,853 METHOD OF TREATING METAL POWDER Frank R. Hemmer, Larchmont, N. Y., assignor to Magnesium Products, Inc., Wilmington, Del., a corporation of Delaware ApplicationApril. 7, 1933, Serial No. 664,933 240mm. (o1. 75-17) This invention relates to the production of metallic magnesium and more particularly to the recovery of the metal in coherent form from a powder containing the same.

In my copending application Serial #542,104, dated June 4, 1931i, and entitled Method ofproducing magnesium I have described a process in which magnesium oxide ore and carbon are caused to react to form magnesium vapors Which are condensed to powder and the powder then treated in a rotary furnace for the production of molten metal. The present application is a continuation in part of the aforesaid application and resides in further developments in that phase of the process described in my original application which is intended to result in a greater and more effective production of coherent metal from the powder.

More particularly, the present invention is designed to protect the magnesium powder before and during the treatment and to provide a treatment which' will increase the amount of liquid metal which is obtained from the powder. This results not only in greater ciiiciency of conversion into salable metal, but also decreases the amount of material remaining and which ordinarily is returned to the smelting furnace for reworking.

The. present invention may be conducted in a number of ways, If a material of the character described in my co-pending application, Serial #664,932, filed April 7, 1933, entitled Method 0f and apparatus for condensing magnesium, is utilized, the procedure in the present case resides in taking the product which consists of a mixture of magnesium powder and a protective liquid, which is ordinarily a hydrocarbon oil. The oil which protects the magnesium from oxidation while in storage, is separated from the powder, but of course leaving the particles of magnesium powder coated with a thin film of oil. The material is charged into a rotary furnace, which is heated to a suitable temperature above the melting point of metallic magnesium and usually below the boiling point at the pressure used. At the same time the material is subjected to a frictional action which may be obtained by rotation of the furnace and thc consequent rubbing ofthe particles on each other and against the walls and the electrodes `of the furnace. In addition thereto or in lieu thereof, other mechanical means for producing this rubbing action may be used.

Because of the presence of the oil at the temperature used for the treatment there is vaporization and'in some cases decomposition thereof,

which has three principal effects. First it drives out of the apparatus any deleterious gases, such asair, which may be present, and thus prevents a change from the metallic condition to that of compounds of magnesium such as oxide, nitride, etc. Second, it prevents access of such gasesrby maintaining a slight positive gas pressure in the apparatus. Third, it provides a reducing atmosphere which may have a beneficial effect in removing combined oxygen, if such exists, from the material being treated. Liquid magnesium is produced in the apparatus and it may be removed Vtherefrom as desired.

If a magnesium powder produced in another manner is used Which does not contain oil', or other protective liquid, but is a finely divided dry powder, the same is stored in an air tight container so as to prevent oxidation or other deterioration thereof. Any air or deleterious vaporizable substances are removed therefrom by means of a vacuum pump. In 'most cases it is preferable to replace the gases removed from the magnesium powder by a gas or even a vaporizable liquid or solid, which is inert in the subsequent rotary furnace operation. 'I'he magnesium powder, thus protected, is then charged into a rotary furnace where it is heated to the proper temperature as explained above and subjected to the rotating action or other action to give friction or rubbing for the production of liquid magnesium; ln this case. it is desirable, though not essential, to maintain the rotary furnace under at least a partial vacuum and in most cases to have the gas remaining in the apparatus of an inert, orreducing character. The vacuum causes vaporization of magnesium, which may be condensed to give purified magnesium. In this 9 case there are combined two treatments, rst a rubbing or frictional action producing crude liquid magnesium and, second, the refining thereof by distillation. Thus, I obtain purified magnesium directly from the powder by a single operation. 9

This results in a higher efficiency of recovery of metal from the powder than when the powder is distilled without the rubbing action.

In the accompanying drawing constituting a part hereof and in which like reference characters indicate like parts:

Figure 1 is an elevational view, partly diagrammatic in character, showing one embodiment of the present invention;

Figure 2 is a similar view of a modified form thereof, and

Figure 3 is a fragmentary view of a slight modication of the system of Figure 2.

Referring to Figure 1, there is provided a storage receptacle 1 for a mixture of magnesium powder and oil. By means of suitable transfer apparatus 2, the mixture is introduced into suitable apparatus 3 for the separation of the oil from the magnesium powder, as by sedimentation, centrifugal action or filtration. The magnesium powder 4 is introduced through the double vacuum valve 5, through duct 6 provided with a pressure-relief valve 7, into a rotary inclined furnace 8. The furnace is provided with bands 9, resting on rollers 10 and suitable means, not shown, is provided for rotating the furnace at the desired speed. Along the inner periphery of the furnace is a series of longitudinal electrodes 11, extending out through the ends of the `furnace and being connected with suitable rings whereby electric current may be passed through the electrodes to provide the proper temperature within the furnace. A spout 12, as is well known, is provided at the discharge end of the furnace, the opening 13 b eing closed by suitable means, which allows liquid to pass out onto spout 12. 'I'he liquid magnesium 14 is received in ladle 15. n

In the operation of the invention the magnesium powder containing some small amount of oil is heated in the rotary furnace to atemperature above the melting point of metallic magnesium, but below the boiling point and the furnace is rotated'so as to give a rubbing action of the particles on each other and on the Walls of the furnace. The electrodes, which provi@ the necessary heat, move continuously through the powder and further subject the powder to frictional action. The heat vaporizes the oil, which forces out any air in the apparatus through the pressure relief valve 7. The atmosphere thus created is somewhat above atmospheric pressure, and therefore, prevents access of air. The atmosphere is of reducing character and assists in the.

reduction of magnesium oxide, if some of this compound is present with the magnesium powder. As` the magnesium assumes the liquid state, itiis discharged through spout 12 and into chill car 15.

Referring to the modification shown in Figure 2, dry magnesium powder is placed in a storage \bin 16, provided with a double vacuum valve 11 for the introduction of material and a similar double vacuum valve 18 for the discharge of the material. A pipe 19 is provided with a valve 20, and is connected with a vacuum pump, not shown. Another pipe 2l provided with a valve 22, allows the introduction into container 16 of a suitable gas, liquid or solid. Secured to the bottom of container 16 is duct 6 which in turn is connected 'to the inlet end lof rotary furnace 8".' In this modification the dischargeend of the furnace is provided with an opening closed by a suitable airy tight cover 23 and the spout 12 is placed in proximity to the lower end of the said furnace. A vacuum-relief valve 24 is provided in duct 6.

In the operation of the invention, the magnesium powder in container or bin 16 is first subjected to a vacuum to draw out all gases and vapors therefrom after which valve 20 is closed and valve 22 is opened, allowngthe introduction of a' suitable gas or liquid which is inert at the temperature of operation of the rotary furnace. Among such materials are hydrocarbon gases or readily volatile liquids, hydrogen, helium and various others. 'I'he gas replaces-the voids in the evacuated powder, which is then discharged by means of valve 18 through duct 6' into furnace 8.

The furnaceis heated and rotated as described above causing liquefaction of the magnesium by the action of the heat and friction. The inert or' reducing gas present acts to protect the magnesium from oxidation. The degree of vacuum in the furnace may be of any desired character. After the operation is completed relief valve 24 is opened to break the vacuum and the sealing device 23 is removed from the opening allowing liquid metal to flow into the chill car 14.

Although I have described my invention setting forth two specific embodiments thereof, the in- I parting from the principles herein set forth. For

instance, in place of valve 24, there may be connected in the system as shown in Figure 3`a condenser 25, and a vacuum pump 26 may be at-4 tached thereto to draw vapors of magnesium from furnace 8 into the condenser to give refined metal. A valve 27 may be placed in the system.

Or a stream of inert gas may be used in place of a vacuum for this purpose. A vacuum is not essential in this modification as the magnesium powder may be heated in the furnace to above its normal boiling point and the vapors condensedv with or without'the aid of a protective gas. My invention is therefore to be construed broadly and not to be limited except as expressed in the appended claims.

What I claim is:

l. A method of treating magnesium powder which' comprisesy mixing therewith a material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, and subjecting said powder to a temperature above the melting point and below the boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce to form liquid metal.

2. A method of treating magnesium powder which comprises mixing therewith a material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, subjecting said powder to a temperature above the melting point and below the' boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce to form liquid metal and preventing access of detrimental gases during said rubbing operation.

3. A method of `treating magnesium powder which comprises mixing vtherewith a gaseous material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, and subjecting said powder to a temperature above the melting point and belo'w the boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce to form liquid metal. l

4. A method of treating magnesium powder which comprises mixing therewith a liquid material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, and subjecting said powder to a temperature above the melting point and below` frio which comprises subjecting the same to atleast a I partial vacuum, mixing therewith a material 4 capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, and subjecting said powder to a temperature above the melting point and below the boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce to form liquid metal.

6. A method of treating magnesium powder which comprises subjecting the same to at least a partial vacuum, mixing therewith a gaseous material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, and subjecting said powder to al temperatureabove the melting point and below the boiling point of magnesium and to a rubbing action to cause magnesium particlesto coalesce to form liquid metal.

7. A method of treating magnesium powder which comprises mixing therewith a gaseous material capable of protecting the magnesium from combining'with deleterious substances'by preventing access thereof, subjecting said powder to a temperature above the melting point and below the boiling point of magnesium and to a ,frubbing action to cause magnesium particles to coalesce to form liquid metal, and providing pressure during said rubbing operation suicient to prevent access of air.

8. A method of treating magnesium powder which comprises mixing. therewith a gaseous material capable of protecting the magnesium from combining with deleterious' substances by preventing access thereof, subjecting said powder to a temperature -above the melting point and below the boiling point of magnesium and to a rubbing action to vcause magnesium particles to coalesce to form liquid metal; and providing a Apressure during said rubbing operation by the heating and consequent expansion of said gaseous material suificient to prevent access of air.

9. A method of treating magnesium powder which comprises mixing therewith a liquid material capable of protecting the magnesium from` combining with deleterious substances by preventing access thereof, subjecting said powder to a temperature above the melting'point and be-V low the boiling point of magnesiumand to a rubbing action to cause magnesium particles to coalesceto form liquid metal, and providing a vgas pressureduring said rubbing operation suincient to prevent access of air.

10. A method of treating magnesium powder. which comprises mixing therewith a liquid material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, subjecting said powder to A a temperature above the melting point and below the boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce l to form liquid'metal', and providing a gas pressure during said rubbing, operation sufcient to pre- 'vent access of air, by the heating and consequent vaporiaation of at least part of said liquid maL terial.

11. A method of treating magnesium powder which comprises mixing therewith a material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, subjecting said powder to a temprature above the melting point and below vthe boiling point of magnesium and to arubbing action to causemagnesium particles to coalesce to form liquid metal and preventing access of air `during said rubbing operation by providing a neutral or reducing atmosphere.

12. A method of treating magnesium powder magnesium vapors formed in said operation Ito form liquid metal.

14. A method of treating magnesium powder which comprises subjecting the same to at least a partial vacuum, mixing therewith a material capable of protecting the magnesium from combining with deleterious substances by preventing access thereof, subjecting said powder to a temperature above the melting point and below the boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce to form liquid metal, releasing the vacuum and removing said metal.

15. A method of treating magnesium powder which comprises subjecting the same to at least a partial vacuum, subjecting said powder vto a temperature above the melting point and belowthe boiling point of magnesium and to a rubbing action to 'cause magnesium particles to coalesce to form liquid metal, releasing the vacuum and removing said metal.

16. A method of treating magnesium powder which comprises subjecting the same toat least .'a partial vacuum, preventing access of deleterious substances and subjecting said powder to a temperature above the melting point and below the boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce to form liquid metal and condensing magnesium vapors formed in said operation.

17. A method of treating magnesium powder which comprises subjecting the same to at least a partial vacuum, -and subjecting said powder to a temperature above vthe melting point and below the boiling point of magnesium and to a rubbing action to cause magnesium particles to coalesce to form liquid metal and condensing a condenser maintained under a partial vacuum.

. 18. A method of treating magnesium powder which comprises subjecting said powder to a tem-'- perature above the melting point and to a rubbing action to cause magnesium particles to coalesce to form liquid metal and condensing magnsium vapors formed in said operation.

I19. A method of treating magnesium powder which comprises subjecting said powder to a temperature above the melting point and to a rubbing action to cause magnesium particles to coalesce to form liquid metal-and condensing magnesium vapors formed in said operation, in the presence of a protective gas.

20. A method of treating magnesium powder 1'40 which comprises lsubjecting' said powder. to a temperature above the melting point and below the boilingl point of magnesium and to a rubbingff action in the presence of an inert or reducing gas to form liquid magnesium. f

21. A method of treating magnesium powderwhich comprises subjecting said powder to `a temperature above the melting point and below the boiling point of magnesium and continuously moving a source of heat through said powder to subject the same to a. rubbing action to form liquid magnesium.

powder in a'continuous state of agitation to form liquid magnesium, providing a. reduced pressure to withdraw vapors of magnesium and condensing the same.

24'. A method of treating magnesium powder which comprises subjecting said powder to a temperature above thel melting point, maintaining said powder ima'continuous state of agitation to' subject the same to a rubbing action, the temperature and pressure being such as to cause vaporization of magnesium, removing the vapors and condensing the same.

\ FRANK R; KEMIWER.

DISOLAlMl-:R

R. Kemmer, Larchmont, N. Y. METHOD F TRETING-METAL Patent dated July 3, f

934. Disclaimer filed Lidy 2l, Q1938, by

the assignee, Magnesium Products, Incorporated. Hereb enters this disclaimer to claim 24 of said patent.

[ ic'ial Gazette June 151938.]

ject the same to a. rubbing action to form liquid magnesium.

powder in a'continuous state of agitation to form liquid magnesium, providing a. reduced pressure to withdraw vapors of magnesium and condensing the same.

24'. A method of treating magnesium powder which comprises subjecting said powder to a temperature above thel melting point, maintaining said powder ima'continuous state of agitation to' subject the same to a rubbing action, the temperature and pressure being such as to cause vaporization of magnesium, removing the vapors and condensing the same.

\ FRANK R; KEMIWER.

DISOLAlMl-:R

R. Kemmer, Larchmont, N. Y. METHOD F TRETING-METAL Patent dated July 3, f

934. Disclaimer filed Lidy 2l, Q1938, by

the assignee, Magnesium Products, Incorporated. Hereb enters this disclaimer to claim 24 of said patent.

[ ic'ial Gazette June 151938.] 

